Measures to reduce iron ore and coal rail track contamination

The Reduction of rail track contamination from iron ore and coal dust project was a collaboration between the University of Newcastle, the National Transport Research Organisation (NTRO), and iMOVE CRC.

The project focused on a significant issue in the heavy haulage rail sector: the substantial accumulation of iron ore, coal dust, and other materials within the train load-out (TLO) system and dumpers.

TLOs are large, bin-like structures built over rail networks and are designed to efficiently load and unload wagons. They are designed to discharge and fill wagons underneath quickly using flood-loading chutes. TLOs are becoming automated, so can achieve high efficiency when running smoothly, achieving initial surge flows as high as 60,000 tonnes per hour. Meanwhile, dumpers aim to discharge content from rail car wagons as fast as possible, with some able to unload up to 11,000 tonnes per hour.

However, imprecise timing and loading can lead to contamination, resulting in inefficient wagon loading, potential derailments, and unreliable monitoring system performance. This can lead to damage to the rail infrastructure.

Background

Rail transportation is crucial to Australia’s economy, supporting more than 164,000 jobs and contributing $30 billion a year. Australia boasts a vast railway network stretching more than 36,000 kilometres. It’s used for passenger and freight, with the latter comprising:

• Bulk (i.e. grains and minerals);
• Non-bulk (container freight cargo, etc.); and
• Heavy haulage (typically for coal and iron ore).

Automated inspection equipment is increasingly used to assess the condition of rail networks. It typically uses ultrasonic and other non-destructive testing and conducts regular measurements and analysis. However, in the resources sector, automated inspection is challenging. Dust and material buildup obscure the view and prevent equipment and personnel from detecting corrosion and fatigue in rail infrastructure.

Dust and material buildup results from spillage/dumping of:

• Lubrication oils;
• Fertilisers
• Organic waste
• Metal ores, and
• Other bulk commodities (typically stored, transported, and handled in loose, granular, or particulate form).

A high moisture content is a significant challenge as it can cause excessive adhesion and cohesion. This is particularly true with coal and ore and may lead to contamination of rail tracks, especially in areas with poorly designed train load-out systems (TLO) that do not efficiently move materials.

When these materials accumulate in particular areas, they create ideal conditions for corrosion. Often there are already harsh conditions in TLO zones in the mining sector. Meanwhile, the most common types of dumpers are rotary cars or bottom-dump. Each of these has advantages and disadvantages.

The current cleaning method is manual and relies on basic water spraying systems. This approach is ineffective at removing contaminants, making it difficult to maintain clean rail surfaces and properly be able to inspect metal and concrete rail footings and clips (which attach the rail to sleepers).

Therefore, track contamination has become an issue with the increased amount of goods and commodities that use the freight rail network.

Objectives

The project team aimed to develop a strategic operation plan to minimise the iron ore and coal contamination of tracks at TLO systems. Two high-level goals were to:

• Improve the understanding of what causes TLO track contamination; and
• Prolong the life of rail in highly corrosive environments using coating sand automated cleaning processes.

The research also sought to investigate non-stick coatings on rail infrastructure to make contamination easier to remove and protect against wear and tear.

These objectives were expected to offer Australasian rail infrastructure system owners and operators several insights to better design for resilience and adapt to climate change. However, the scope of the research did not include train derailments or improper handling and transportation that led to chemical spillages that contaminated the rail network. Chemical spills from train derailments or improper handling or transportation can also contaminate tracks.  However, they are outside the scope of this project.

Literature review

There was a lack of literature on how to remove iron ore spillages from rails efficiently and attend to the potential long-term effects on the structural integrity of rail components. Very little research had explored reducing contamination levels at TLOs. Generally, research had focused on the effects of contamination on the surrounding environment.

The literature shows that many railways with widespread contamination require many different cleaning methods. They include brushing, scrubbing, and vacuuming. However, for localised, severe contamination in specific areas, these methods, such as manual high-water-pressure enabled cleaning, are often too expensive or impractical. This creates a need for cost-effective solutions in regions like train load-out areas, dumpers, and tunnels.

Scrubbing attachments for rail cleaning

In industry, many complications can arise from moderate to severe levels of contamination. Those areas explored, include increased wear and corrosion, and importantly the inability to identify faults within the network from both visual inspection and scanning equipment.

Unfortunately, many academic researchers have not explored this area of concern, however, there are many benefits in solving such a prominent problem, including the decreased maintenance and replacement costs, reduced down-time and increase the overall efficiency of the system.

It is common, however, to use more drastic methods to reduce corrosion, wear and other problems associated with excess contaminants including alloying, which in many cases is not an appropriate solution.

Methodology

Many companies have employed software to predict how bulk material will behave on a molecular level when decanted. This is called Discrete Element Method (DEM) software and a particular type, Ansys Rocky, was used to calibrate flow and for further testing in this project. Ansys Rocky offers insights into particle friction, rolling resistance and adhesion.

However, the project team selected these specific models and contacts among those that Ansys Rocky offers:

• Normal Force Models (hysteretic linear spring model, linear spring-dashpot model and the Hertzian spring-dashpot model);
• Tangential Force Models (linear spring Coulomb limit model, Coulomb limit model and the Mindlin-Deresiewicz model);
• Adhesive Force Models (the constant adhesive force model, linear adhesive force model and the JKR (Johnson-Kendall-Roberts) adhesive force model)
• Rolling Resistance Models (constant moment and type C: linear spring rolling limit); and
• Smoothed Particle Hydrodynamics Method.

Results

While the project successfully developed and tested several designs to remove contaminants and minimise wear and corrosion, they were only theoretical or briefly tested for validation.

The researchers found that a 2mm ultra-high-built enamel protective coating on rail components was most effective in reducing wear and tear and boosting a cleaning system’s effectiveness. Thicker layers of this enamel could be used, too. The test time spanned 400 days.

In the rail industry, like most industries, there are many factors to consider when choosing suitable protective coatings, including the environment, geometry, and component function. The coatings selected for wear, corrosion and friction testing are all high-grade protective paints, however, many failed prematurely, highlighting the extreme conditions observed at such areas.

The project team found a pressurised or high-flow water system worked well to remove contaminants from specific areas. However, the direct stream did not allow for debris removal in other areas. A larger spray zone or more nozzles could help, but these would affect the mass flow and consequently reduce the effectiveness of removing materials. As well, using water in remote and dry areas for this work may not be sustainable due to the scarcity of this resource there. A possible solution is to recycle the cleaning water by incorporating lower-lying tanks to capture and filter the debris.  Even with this design improvement, the water may be more problematic due to having higher minerals, but coatings could negate this. The study validated a secondary high-pressure water system, including nozzles under the rail navigating vehicle and, if automated, showed promise for mining and transportation industries.

As for the team’s observation of the physical testing of manual and automated scrubbing systems, this approach was problematic due to signs of dust. Australia has tightening restrictions on dust generation from moving vehicles, stockpiles, and handling operations that can significantly impact nearby infrastructure and personnel. Applying water to suppress dust is a solution but raises the issue of water getting to the rail clips, thereby leading to corrosion.

The proposed implementations were designed for existing mining and rail infrastructure with short lifespans or limited budgets, avoiding costly redesigns and new construction.

Future directions

There are three ways forward for this project:

• Redesign existing TLO systems and dumpers to include a grid-like structure with elevated rails below;
• Optimise the design of cleaning methods, such as a high-pressure water system; and
• Design and manufacture an automated scrubbing system that is to scale. The system would be self-driving on railway tracks and use train wheels to traverse the rail network. For example, while autonomous vehicles already exist, few include an effective automated cleaning system, particularly vacuums that remove debris loosened by brush in heavily contaminated areas.

Autonomous vehicle prototyped by the University of Newcastle and participating organisations.

Expected project impacts

“Rail track wear and corrosion from dust and material buildup is a significant and costly issue in the heavy haul rail sector. The project’s research into enamel protective coatings on rail components and experimental design of sustainable and cost-effective improved methods for removing contaminants from rail tracks should set the foundation for developing full scale automated cleaning solutions that will prolong the life of rail infrastructure in train load-out (TLO) systems.”

Paul Bennett, Senior Technology Leader, Asset Performance, Transport Futures at the National Transport Research Organisation (NTRO)

Final report

A final report has been produced, but is for internal use only.